Late fee waiver for delayed GSTR-3B filings extends limited grace periods for specified taxpayers for select months. Amendment inserts a proviso waiving the late fee under Section 47 for specified classes of registered persons who fail to furnish returns in FORM GSTR-3B, setting distinct grace periods by class and tax period for March-April 2021 and January-March 2021, and declaring the amendment effective from 20 April 2021.